ModifyingDarkMatterFreezeOutat theElectroweakPhaseTransition - PowerPoint PPT Presentation

Modifying
Dark
Matter
Freeze
Out
at the
Electroweak
Phase
Transition Andrew
Long University
of
Wisconsin,
Madison with
D.J.H.
Chung,
S.
Tulin,
L.T.
Wang EWPT ρ φ expansion DM
f.o. Tuning H fo Ω ρ Λ

Collider
& Cosmology
&
 Will
they (In)Direct
Search Astronomy match?

Suppose
they don’t
match! What
went
wrong?
‐‐
We
should
not
 assume 
radiation
dominates
at
freeze
out [Kolb & Wolfram, 1980] - Tune CC against SM Higgs vacuum energy [Barrow, 1982] - Anisotropic expansion boosts relic abundance [McDonald, 1990] - Decaying massive particles dominate ρ at freeze out [Kamionkowski & Turner, 1990] - “Thermal Relics: Do we know their abundance?” [Joyce, 1997] - Kination dominated scalar field modifies H at EWPT [Salati, 2003] - Quintessence modifies H at freeze out [Profumo & Ullio, 2003] - Kination dom. quintessence modifies χ 0 abundance [Megevand & Sanchez, 2008] - Entropy production at first order PT & dilutes relic [Wainwright & Profumo, 2009] - Entropy production saves SUSY models Andrew Long - 3

Suppose
they don’t
match! What
went
wrong?
‐‐
We
should
not
 assume 
radiation
dominates
at
freeze
out Additional
contribution
to ρ from
scalar
&
tuned
cosmological
constant Larger Ω DM Larger
H Γ ∼ H
earlier Andrew Long - 4

Mismatch Suppose
they signals
new
physics
in
Higgs don’t
match! sector
&
CC
tuning What
went
wrong?
‐‐
We
should
not
 assume 
radiation
dominates
at
freeze
out Additional
contribution
to ρ from
scalar
&
tuned
cosmological
constant Larger Ω DM Larger
H Γ ∼ H
earlier Andrew Long - 4

Cosmological
History Standard freeze
out EWPT Cosmology during ρ r domination V V V e e G e G G 0 0 0 1 1 1 BBN ( ρ r dom.) Modified Cosmology phase
transition supercooling completes freeze
out ρ φ + ρ Λ ∼ ρ r while
H
boosted Andrew Long - 5

H
at
EWPT
&
Tuning
CC The
Calculation : 1)

Calculate
thermal
effective
potential
V T ( φ )‐‐free
energy
 density
of
a
gas
at
temperature
T
coupled
to
condensate
 φ 2)

Tune
CC
against
scalar
vacuum
energy
at
zero
temperature 3)

Calculate Δ H/H
as
a
function
of
temperature 4)

(Embed
scalar
sector
into
a
model
of
DM
with
freeze
out
 occuring
before
or
during
EWPT
when
 Δ H/H
is
maximal) Andrew Long - 6

Second
Order
PT
&
SM Standard
Model
phase
transition tuning
CC c 1 
~
h t 2 
+
g 2 Why
is Δ H/H
so
small? solution
=
 Same
parameters
control
vacuum • supercooling energy
&
temperature:

V(T)/T 4 
 ∼ 
O(1) Hard
to
beat
g * 
 ∼ 
100
suppression • Andrew Long - 7

First
Order
PT
&
xSM •

The
Hubble
parameter
receives
a
larger
correction
when the
universe
is
suspended
in
a
metastable
phase •

Then,
 Δ H/H
 ∼ 
V/T 4 
grows
at
T
drops tuning
CC •

Real
singlet
extension
admits
a
1PT [Ramsey-Musolf, et. al., 2007] gauge singlet at
T ∼ T c ,
metastable minimum
here Andrew Long - 8

(1) Symmetry restored at high temperature Andrew Long - 9

(2) Origin becomes metastable below critical temperature Andrew Long - 9

(3) During supercooling, Δ H/H grows like 1/T 4 in metastable phase freeze out now! Andrew Long - 9

(4) At a lower temperature the PT completes Andrew Long - 9

Summary
‐‐
What
to
do
if 1) 
DM
relic
abundance
can
be
enhanced
by
O(10%)
if
freeze
out
occurs
during
a first
order
electroweak
phase
transition 2) 
Favors: a) Extended
scalar
sector b) Low
temperature
phase
transition
&
high
temperature
freeze
out
(10s
GeV) heavy
dark
matter
favored
by
PAMELA c) Sufficient
supercooling


















strongly
first
order
phase
transitions
allow
for interesting
physics
such
as
baryogenesis
and
gravity
waves 3) 
Mismatch
between
cosmological
and
collider‐inferred relic
abundance
may
provide
evidence
for
a
link
between
dark matter,
the
Higgs
sector,
and
tuning
of
the
cosmological
constant EWPT ρ φ expansion DM
f.o. Tuning H fo Ω ρ Λ Andrew Long - 10